Berlusconi told an Italian radio station that he had struck the deal with Roberto Maroni, leader of the regionalist League, which was coalition partner in his last government.

According to the agreement, Berlusconi's People of Freedom (PDL) party would support Maroni's candidacy for president of the northern region of Lombardy as part of a global deal.

He did not give other details of the accord but said he would be the "leader of moderates" in a centre-right coalition with the League.

The League supports stringent policies on immigration and favours giving more power and autonomy to Italy's 20 regions.

It particularly wants more of the tax revenue that now goes to the national government to go directly to the regions, saying that the rich north is picking up the tab for a south it sees as corrupt and economically sluggish.

Maroni was holding a news conference later on Monday.

Berlusconi, who left office in November 2011 to make way for a technocrat government led by Mario Monti, said it was still not certain who would be prime minister in a centre-right government.

"We will decide if we win," he said, adding that he would prefer to be the economy minister and that mostly likely PDL secretary Angelino Alfano would be the prime minister.

An opinion poll published on Sunday suggested an alliance between the PDL and the League could pull in about 28 percent of the vote.

A centre-left coalition led by Pier Luigi Bersani of the Democratic Party would win between 38 and 39 percent, the poll found.  Monti's centrist bloc would get between 14 and 15 percent, it said.

Berlusconi, who supported Monti's government until last month, attacked him for re-introducing a much-hated property tax on primary residences and promised to reduce income taxes.

Both Berlusconi and Monti have been making numerous appearances on television and radio ahead of the February 24-25 elections.